It is often desirable to be able to easily tilt certain types of apparatus in a given plane and to swivel it about a vertical axis in order to make it easier to see images formed thereon and to adjust various controls. Mounting assemblies for this purpose have been comprised of a base that can be secured to a table top and a platform on which the apparatus is mounted that can be tilted and swiveled with respect to the base. These functions are provided by a spherically shaped bottom surface on the platform that rests in an upwardly extending annular ridge on the base and a straight slot in the spherical bottom of the platform through which a vertical pivot pin that is rigidly mounted to the base extends. The platform can only be tilted in the vertical plane of the slot and can be rotated about the pivot pin regardless of where it is in the slot. Leads or tubes required for operation of the apparatus are passed between the apparatus and the platform, through an aperture in the bottom spherical surface and an opening in the base that lies inside the annular ridge. The amount of swivel is limited by the leads coming in contact with an edge of the opening in the base. This is undesirable as sufficient force can easily be applied to the leads to cause them to be pulled loose. Furthermore, the angle through which the platform can be swiveled is limited if the pivot pin is to be inexpensively and securely mounted. Any arrangement of simple means for limiting the angle of swivel so as to avoid contact between the wires and tubes and the edges of the opening in the base is complicated by the tilting of the platform with respect to the base.